This invention relates to optical memories having a plurality of data tracks per data channel and, more particularly, to methods and means for reading out such data tracks selectively or in parallel.
Digital optical disks are now being seriously considered as potential alternatives to magnetic tape and disk memories. It has been found that optical disks offer a substantially greater data storage capacity than commercially available magnetic tape or disk memories of similar size. See, for example, Kenney et al., "An Optical Disk Replaces 25 Map Taps", IEEE Spectrum, February 1979., p. 33.
As is known, a digital optical disk may be configured to have one or more bands of tracks. A continuous, spirally configured track band format is well suited for applications involving long continuous runs of digital data, while a format providing a plurality of concentric track bands may sometimes be better for applications requiring random access to selected memory locations. Regardless, however, of the format selected, there typically are several data tracks per band.
Heretofore, the conventional practice has been to selectively read out the data tracks of an optical memory one track at a time. That is sufficient for many purposes, but imposes a potentially troublesome limitation on the output bandwidth of such a memory.